The field of the present invention is that of teach tools for teaching a programmable robot to follow a prescribed multi-dimensional path along a three dimensional work piece. More particularly the present invention relates to a pointer which allows an operator to teach a programmable robot to follow a multidirectional path along a three dimensional work piece while keeping an end of arm tool at a prescribed angle with respect to an instantaneous surface of the work piece and also to keep the tool at a fixed distance away from the instantaneous surface of the work piece.
Most automotive vehicles have a roof. The roof of the automotive vehicle is typically joined to the remainder of the car body by at least a pair of transversely spaced front and rear pillars. The front pillars which are adjacent to the windshield are referred to as the A pillars. The rear pillars which are adjacent to the rear window opening are typically referred to as the C pillars.
The C pillar""s outer body is formed from two large sheet metal stampings. The first stamping is the roof panel. The second stamping is a rear quarter panel. The roof panel has an integral portion forming a depression for placement of the rear glass window pane and for forming an upper portion of the C pillar.
The roof panel portion of the C pillar is typically placed in an over-lapping manner in connection with a C pillar portion of the rear quarter panel. The rear quarter panel also has a depression for the rear window pane. The rear quarter panel additionally forms the rear door opening and the rear side panel of the vehicle. For aesthetic reasons, it is typically desired that the C pillar appear to be one continuously formed piece of sheet metal.
To cover up the seam overlap between the roof panel C pillar portion and the quarter panel C pillar portion, brazing is typically applied. After the brazing solidifies, a grinder is applied to smooth out the brazing to provide a smooth transition between the sheet metal of the C pillar which is integral with the roof panel and the sheet metal which is integral with the rear quarter panel. After the grinding operation and subsequent painting of the vehicle the seam line between the two sheet metal portions of the C pillar becomes virtually indistinguishable.
In the most recent two decades, efforts have been made to utilize robots to perform the brazing operation. To project the brazing (sometimes referred to as solder) upon the C pillar there is a device which is typically referred to as a brazing nozzle. The brazing nozzle projects liquefied silicon brazing material onto the C pillar. The C pillar on most vehicles has a surface curvature in the fore and aft direction and also has a curvature in the transverse direction of the vehicle as well as the vertical direction.
Accordingly, the brazing gun at the end of the robot must follow a complex multi-dimensional path. The brazing nozzle should be maintained at a perpendicular orientation with respect to the surface of the C pillar. Additionally, the brazing nozzle should also be positioned at a constant distance from the surface of the C pillar to provide an even disposition of brazing and also to prevent excessive heat transfer to the C pillar which could inadvertently warp or damage the sheet metal of the C pillar.
Emperical experience has shown that the complex geometrical shapes of the C pillar make a purely mathematical modeling of the path of the robot to be unworkable. Accordingly, to program the robot a teach tool is utilized. When using a teach tool an operator will physically manipulate the robot in the desired path of operation. The motion imparted to the robot will be transferred to its controller and the robot will xe2x80x9cmemorizexe2x80x9d the path followed by the teach tool. Thereafter the robot can follow the prescribed path in a repeatable fashion.
Prior to the present invention, a rod like pointer was used as the teach tool for the robot. When using a rod pointer, sometimes inadvertently the operator teaching the robot would not have the pointer perpendicular to the instantaneous surface of the C pillar. Because the pointer as not perpendicular to the surface, several problems would occur when the robot was brazing the C pillar using the brazing nozzle. When the nozzle was not perpendicular to the surface, the brazing is sometimes misapplied and whenever the pointer is not perpendicular to the surface, the distance from the brazing nozzle to the surface of the C pillar is not constant.
Such a non-constant or variable distance causes the brazing to be misapplied and can sometimes inadvertently cause the sheet metal of the C pillar to be overexposed to heat causing it to warp or bend. To compensate for the lack of a constant distance of the brazing gun away from the sheet metal surface typically an excess amount of brazing was applied. The excess amount of brazing was undesirable since additional brazing time causes an increase in production time. Also, the additional brazing mandates additional production time for the grinding operation to smooth out the brazing.
It would be desirable to provide a teach tool which would ensure that an end of arm tool such as a brazing nozzle can be robotically manipulated on a resetting work piece along a multi-dimensional path while at the same time keeping a constant perpendicular angle to an instantaneous surface of the C pillar and also being at a constant distance therefrom.
The present invention provides a pointer to teach a robot to repetitively manipulate an end of arm tool such as a brazing nozzle having a predetermined length along a multi-dimensional path on a resetting work piece as provided by a C pillar of an automotive vehicle body. The pointer is utilized to teach the robot to keep the brazing nozzle at a generally perpendicular work angle and at a preselected work distance away from instantaneous surface of the C pillar along the multi-dimensional path.
The invention includes a base portion connecting the pointer with an end of a robot arm. A main body having an elongated form with a generally rectangular cross-section is connected with the base portion. The main body has a length inclusive of the base approximating the predetermined length of the brazing nozzle and the preselected desired work distance of the brazing nozzle away from the surface of the C pillar.
A contact portion which is continuous and integral with the main body is provided for contacting the C pillar. The contact portion has two small parallel spaced surface flats which are generally aligned in a common plane perpendicular with respect to the robot arm. The flats are separated by a window cut out to allow an operator to visually inspect the instantaneous surface of the C pillar juxtaposed by the flats.
It is an object of the present invention to provide a pointer which can be utilized in teaching a robot to manipulate an end of arm tool such as a brazing gun at a constant distance along a multi-dimensional path along a three-dimensional work piece.
It is also an object of the present invention to provide a pointer which can be used to teach a robot to repetitively manipulate an end of arm tool such as a brazing nozzle at a constant angle with respect to an instantaneous surface of a three-dimensional object along a multi-dimensional work path.
The above-noted objects of the present invention will become apparent to those skilled in the art from a review of the invention as it is provided in the accompanying drawings and detailed description of the invention.